Dual effect of dynorphin on the non-adrenegic inhibitory potentials and the spontaneous action potentials in the duodenal smooth muscle cells of the guinea-pig

1985 ◽  
Vol 111 (1) ◽  
pp. 139-140 ◽  
Author(s):  
Hiromichi Ohkawa
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Action Potentials ◽  
Muscle Cells ◽  
Dual Effect ◽  
Spontaneous Action ◽  
Spontaneous Action Potentials

Ionic basis of the action potential of guinea pig gallbladder smooth muscle cells

1993 ◽  
Vol 265 (6) ◽  
pp. C1552-C1561 ◽  
Author(s):  
L. Zhang ◽  
A. D. Bonev ◽  
M. T. Nelson ◽  
G. M. Mawe
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Action Potential ◽  
Smooth Muscle Cells ◽  
Action Potentials ◽  
Outward Current ◽  
Muscle Cells ◽  
Tetraethylammonium Chloride ◽  
Voltage Dependent ◽  
Calcium Activated Potassium Channels

Smooth muscle cells in the intact guinea pig gallbladder had a resting membrane potential of about -45 mV and had spontaneous action potentials that consisted of a rapid depolarization, a transient repolarization, a plateau phase, and a complete repolarization. These action potentials lasted approximately 570 ms and occurred at a frequency of approximately 0.4 Hz. Action potentials were abolished by the dihydropyridine (DHP)-sensitive Ca2+ channel blocker nifedipine (1.0 microM) and were enhanced by the DHP-sensitive Ca2+ channel agonist BAY K 8644 (0.5 microM). The K+ channel blockers tetraethylammonium chloride (5.0 mM) and 4-aminopyridine (4-AP; 2.0 mM) prolonged the action potential, whereas charybdotoxin (100 nM), a blocker of calcium-activated potassium channels, had no effect. Whole cell currents were characterized in enzymatically isolated smooth muscle cells from the same preparation. 4-AP, a blocker of voltage-dependent K+ channels, suppressed 70% of the outward current at 0 mV. Charybdotoxin (100 nM) reduced an additional 15% of the current at 0 mV. Single calcium-activated potassium channels were identified. The potential for half-activation of these channels, at a cytosolic Ca2+ concentration of 100 nM, was 66.8 mV. A fivefold increase in cytosolic Ca2+ resulted in a shift of the activation curve by -53 mV. External tetraethylammonium chloride (200 microM) reduced the mean single channel current by 48% at 0 mV. The whole cell outward current was abolished by replacement of intracellular K+ for Cs+. Ca2+ currents were inhibited by nifedipine and were increased by BAY K 8644. We conclude that DHP-sensitive voltage-dependent Ca2+ channels are responsible for the depolarization of the action potentials and that the repolarization is due to primarily 4-AP-sensitive K+ current.

scholarly journals Local Ca2+transients and distribution of BK channels and ryanodine receptors in smooth muscle cells of guinea-pig vas deferens and urinary bladder

2001 ◽  
Vol 534 (2) ◽  
pp. 313-326 ◽  
Author(s):  
Yoshiaki Ohi ◽  
Hisao Yamamura ◽  
Norihiro Nagano ◽  
Susumu Ohya ◽  
Katsuhiko Muraki ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Urinary Bladder ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Vas Deferens ◽  
Ryanodine Receptors ◽  
Muscle Cells ◽  
Bk Channels
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